[security] wiping out the /pxe/nfs folder

[xiorcale]

When an administrator removes a device, the shell script takes the given hostname and erase the folder with the same name in /pxe/nfs. If someone give * as a name, the entire folder would be wiped out.

Since this feature requires admin rights, I guess it is not in their best interest to do that, but still, "escaping" any wild card would do the trick and insure us nothing monstrous will happen.